This application is a 35 U.S.C. 371 application of and claims priority to PCT/EP00/07486, the international filing date of which is Aug. 2, 2000, which claims priority to German application no. 19936324.2 filed on Aug. 2, 1999. This 371 application claims priority to German application no. 19936324.2 filed on Aug. 2, 1999. The content of each of these applications is hereby fully incorporated by reference.
The invention relates to a mixture and a process for the treatment of waste materials and the use of this mixture in the treatment of waste materials.
Normally, waste materials are either disposed without treatment or after incineration in an incinerator. It is of importance that waste materials after leaching with water keep defined threshold values for contaminants. These contaminants may be heavy metals for example Cd, Cr, Hg, Cu, Ni or Pb, and/or organic contaminants. For this purpose waste materials are treated with cement and/or other materials with pozzolanic properties.
In another such process, a waste material such as fly ash is washed to neutral wherein soluble salts are dissolved and thereby washed out. In a next step, the suspension is drained and the dewatered material is mixed with a binding agent, such as cement. The pasty mixture is cast for hardening either in blocks or is disposed directly on a landfill. Alternatively, fly ash and filter cake from the incinerator may be mixed directly with binding agents and clay.
A disadvantage of these processes is the relatively high consumption of cement and combined therewith a large volume increase and high cost. In addition, traditional processes are insufficient to prevent the leaching of ecologically hazardous contaminants from treated waste materials.
Waste materials are increasingly being re-used. A lot of waste materials, for example lime sludge or sludge from wastewater treatment, include valuable contents such as CaO, Al2O3 and silicate. These can be re-used for clinker production in cement production. Clinker is an intermediate product for the production of cement, which is usually produced from natural raw meal consisting essentially of CaO, Al2O3, SiO2 and Fe2O3. Part of the natural raw meal can be replaced depending on the composition of the waste material.
In the case of re-use, it is also necessary that the re-used waste materials do not exceed certain threshold values for the leaching of contaminants such as heavy metals.
Therefore, the problem underlying the invention was to provide a mixture and a process for the treatment of waste materials, which overcome the above shortcomings.
In one aspect, the invention provides a mixture suitable for treatment of waste materials. The mixture includes (A) at least one zinc salt of a saturated or unsaturated aliphatic or aromatic carboxylic acid, (B) at least one calcium salt of a saturated or unsaturated aliphatic or aromatic carboxylic acid, (C) at least one hydrophobing agent, (D) at least one amino alcohol, and (E) NH3.
In another aspect, the invention provides a process for the treatment of waste materials. The process includes adding a mixture to waste material, and mixing of the mixture and waste material. The mixture may include (A) at least one zinc salt of a saturated or unsaturated aliphatic or aromatic carboxylic acid, (B) at least one calcium salt of a saturated or unsaturated aliphatic or aromatic carboxylic acid, (C) at least one hydrophobing agent, (D) at least one amino alcohol, and (E) NH3.
In yet another aspect, the invention provides a treated waste material made by a process comprising adding a mixture to waste material and mixing the mixture and the waste material to form the treated waste material. The mixture may comprise at least one zinc salt of a saturated or unsaturated aliphatic or aromatic carboxylic acid, (B) at least one calcium salt of a saturated or unsaturated aliphatic or aromatic carboxylic acid, (C) at least one hydrophobing agent, (D) at least one amino alcohol and (E) NH3.